<form style="padding: 10px; text-align:center; margin-bottom: 30px;"
      action="https://tinyletter.com/xmpp" method="post" target="popupwindow"
      onsubmit="window.open('https://tinyletter.com/xmpp', 'popupwindow',
      'scrollbars=yes,width=800,height=600');return true">
<p><label for="tlemail">Subscribe to the XMPP newsletter</label></p>
<p><input type="text" placeholder="Email address" name="email" id="tlemail" /></p>
<input type="hidden" value="1" name="embed"/>
<input type="submit" style="padding: 10px; border-radius: 5%" value="Subscribe" />
</form>
